If an enzyme name is shown in bold, there is experimental evidence for this enzymatic activity.
Locations of Mapped Genes:
|Superclasses:||Biosynthesis → Amino Acids Biosynthesis → Proteinogenic Amino Acids Biosynthesis → L-threonine Biosynthesis|
The overall superpathway of threonine biosynthesis as shown here covers the entire process of converting the central energy metabolism molecule oxaloacetate into threonine.
This pathway is regulated at multiple points by its end product, both via enzyme inhibition and attenuation. Attenuation in response to isoleucine and threonine represses the second, fourth, fifth, and sixth steps in this pathway. In addition, the enzymatic activity of ThrA is inhibited by threonine, regulating flux through the second and fourth steps in the pathway.
The presence of three enzymes carrying out the second step and two enzymes carrying out the fourth step in the threonine biosynthesis pathway reflects the many downstream products that depend on those reaction steps. Look at the superpathway of L-lysine, L-threonine and L-methionine biosynthesis I for a full explanation of the overarching regulatory relationships affecting these pathway steps.
Shames84a: Shames SL, Ash DE, Wedler FC, Villafranca JJ (1984). "Interaction of aspartate and aspartate-derived antimetabolites with the enzymes of the threonine biosynthetic pathway of Escherichia coli." J Biol Chem 1984;259:15331-15339. PMID: 6150934
Almo94: Almo SC, Smith DL, Danishefsky AT, Ringe D (1994). "The structural basis for the altered substrate specificity of the R292D active site mutant of aspartate aminotransferase from E. coli." Protein Eng 7(3);405-12. PMID: 7909946
Alvarez04: Alvarez E, Ramon F, Magan C, Diez E (2004). "L-cystine inhibits aspartate-beta-semialdehyde dehydrogenase by covalently binding to the essential 135Cys of the enzyme." Biochim Biophys Acta 1696(1);23-9. PMID: 14726201
Angeles89: Angeles TS, Smanik PA, Borders CL, Viola RE (1989). "Aspartokinase-homoserine dehydrogenase I from Escherichia coli: pH and chemical modification studies of the kinase activity." Biochemistry 28(22);8771-7. PMID: 2557908
Angeles90: Angeles TS, Viola RE (1990). "The kinetic mechanisms of the bifunctional enzyme aspartokinase-homoserine dehydrogenase I from Escherichia coli." Arch Biochem Biophys 283(1);96-101. PMID: 2241177
Bearer78: Bearer CF, Neet KE (1978). "Threonine inhibition of the aspartokinase--homoserine dehydrogenase I of Escherichia coli. A slow transient and cooperativity of inhibition of the aspartokinase activity." Biochemistry 1978;17(17);3523-30. PMID: 28752
Bearer78a: Bearer CF, Neet KE (1978). "Threonine inhibition of the aspartokinase--homoserine dehydrogenase I of Escherichia coli. Stopped-flow kinetics and the cooperativity of inhibition of the homoserine dehydrogenase activity." Biochemistry 17(17);3517-22. PMID: 28751
Belfaiza84: Belfaiza J, Fazel A, Muller K, Cohen GN (1984). "E. coli aspartokinase II-homoserine dehydrogenase II polypeptide chain has a triglobular structure." Biochem Biophys Res Commun 123(1);16-20. PMID: 6383377
Biellmann80: Biellmann JF, Eid P, Hirth C, Jornvall H (1980). "Aspartate-beta-semialdehyde dehydrogenase from Escherichia coli. Purification and general properties." Eur J Biochem 1980;104(1);53-8. PMID: 6102909
Biellmann80a: Biellmann JF, Eid P, Hirth C (1980). "Affinity labeling of the Escherichia coli aspartate-beta-semialdehyde dehydrogenase with an alkylating coenzyme analogue. Half-site reactivity and competition with the substrate alkylating analogue." Eur J Biochem 1980;104(1);65-9. PMID: 6102911
Birolo95: Birolo L, Sandmeier E, Christen P, John RA (1995). "The roles of Tyr70 and Tyr225 in aspartate aminotransferase assessed by analysing the effects of mutations on the multiple reactions of the substrate analogue serine o-sulphate." Eur J Biochem 232(3);859-64. PMID: 7588727
Birolo99: Birolo L, Malashkevich VN, Capitani G, De Luca F, Moretta A, Jansonius JN, Marino G (1999). "Functional and structural analysis of cis-proline mutants of Escherichia coli aspartate aminotransferase." Biochemistry 38(3);905-13. PMID: 9893985
Bonner90: Bonner CA, Fischer RS, Ahmad S, Jensen RA (1990). "Remnants of an ancient pathway to L-phenylalanine and L-tyrosine in enteric bacteria: evolutionary implications and biotechnological impact." Appl Environ Microbiol 56(12);3741-7. PMID: 2082822
Broglie83: Broglie KE, Takahashi M (1983). "Fluorescence studies of threonine-promoted conformational transitions in aspartokinase I using the substrate analogue 2'(3')-O-(2,4,6-trinitrophenyl)adenosine 5'-triphosphate." J Biol Chem 1983;258(21);12940-6. PMID: 6313682
Cassan75: Cassan M, Boy E, Borne F, Patte JC (1975). "Regulation of the lysine biosynthetic pathway in Escherichia coli K-12: isolation of a cis-dominant constitutive mutant for AK III synthesis." J Bacteriol 123(2);391-9. PMID: 238953
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